‘National interest’

“I cannot conceive of circumstances where Labour MPs are marshalled to go through the lobby and vote against us staying in the customs union and the single market, with the likes of Jacob Rees-Mogg, Boris Johnson and Michael Gove,” said Mr Umunna.

Both MPs insisted they were acting in the “national interest,” which they said transcended party politics.

Lib Dem leader Sir Vince Cable, who is campaigning for another referendum, said: “It is good to see cross-party cooperation between Tory and Labour rebels.”

He said he was “optimistic that the rebellions in both Tory and Labour parties will spread in coming weeks”, and that his party was working with them in the House of Lords.